A Bailey bridge is a type of portable, pre-fabricated, truss bridge. It was developed in 1940-1941 by the British for military use during World War II and saw extensive use by British, Canadian and US military engineering units. A Bailey bridge has the advantages of requiring no special tools or heavy equipment to assemble. The wood and steel bridge elements were small and light enough to be carried in trucks and lifted into place by hand, without requiring the use of a crane. The bridges were strong enough to carry tanks. Bailey bridges continue to be used extensively in civil engineering construction projects and to provide temporary crossings for foot and vehicle traffic.

In China, the early Bailey Bridge was mainly used in military military steel bridges. Now, besides the war steel bridge, the Bailey Bridge has been widely used in disaster relief, traffic engineering, and dangerous bridge reinforcement. For example, during the 5.12 earthquake in 2008, there were a large number of Bailey Bridges used for disaster relief. The Bailey Bridge played a key role in fighting the earthquake relief materials, sending the wounded and evacuating the people.